Adipokines, inflammation, and the endothelium in diabetes

Cytokines are biologically active low molecular weight proteins that possess several endocrine and metabolic functions and are known products of the immune system and inflammation. Several of these cytokines were shown to be independent risk factors for cerebrovascular and coronary artery disease. Because visceral and subcutaneous adipose tissues are the major sources of cytokines (adipokines), increased adipose tissue mass is associated with alteration in adipokine production (eg, overexpression of tumor necrosis factor-α [TNF-α], interleukin-6 [IL-6], plasminogen activator inhibitor-1 [PAI-1], and underexpression of adiponectin in adipose tissue). The proinflammatory status associated with these changes provides a potential link between insulin resistance and endothelial dysfunction, the early stage in the atherosclerotic process, in obese individuals, and in type 2 diabetic patients. Reduction of adipose tissue mass through weight reduction in association with exercise reduces TNF-α, IL-6, and PAI-1, increases adiponectin, and is associated with improved insulin sensitivity and endothelial function.